JP3634144B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a fax machine, and more particularly to an image forming apparatus having a transfer belt means for transferring an image on an image carrier onto a transfer material.
[0002]
[Prior art]
A conventional image forming apparatus used in a copying machine or the like has a transfer belt unit for transferring a toner image formed on an image carrier such as a photoconductor to a transfer material such as a recording paper. For example, as disclosed in Japanese Patent Application Laid-Open No. 9-281815, one having a transfer belt offset mechanism is employed.
[0003]
The detent mechanism includes a plurality of rollers including a drive roller having a guide groove formed on one end side in the circumferential direction, and winds these rollers and a long guide rib at a position corresponding to the guide groove. The transfer belt means comprises a transfer belt fixed in a direction. When the transfer belt is driven to rotate by the drive roller, the guide rib rotates with the transfer belt while being placed in the guide groove, and the position of the transfer belt is regulated by the guide rib. Is prevented.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional image forming apparatus, the position restriction and the detent of the transfer belt are performed only on one end side of the transfer belt. For this reason, when the driving roller is driven, there is a problem that wrinkles are generated on the transfer belt if a compression force is applied to the transfer belt due to its position restriction. In particular, in order to increase the driving force of the transfer belt, when the frictional force of the winding surface between the driving roller and the transfer belt is increased and driving is performed in all the sub-regions of the winding surface, the wrinkles are likely to occur.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus provided with transfer belt means that does not cause wrinkles on the transfer belt even when the transfer belt is deviated only on one end side thereof.
[0006]
[Means for Solving the Problems]
The image forming apparatus of the present invention that achieves the above object includes a plurality of rollers including a driving roller having guide grooves formed in the circumferential direction outside the transfer region, and the guides in the longitudinal direction while winding the rollers. A transfer belt means having a guide rib at a position corresponding to the groove, and the transfer belt means drives the transfer belt by the rotation of the drive roller to transfer the image formed on the image carrier. In the image forming apparatus for transferring to a predetermined transfer material after copying on the transfer belt, the drive roller drives the transfer belt with a high friction surface in a part near the guide groove of the drive roller. has a feature, the drive roller has a high friction surface all around the partial region of the guide groove vicinity.
[0007]
The high friction surface is preferably coated with metal powder.
The high friction surface and the peripheral edge of the guide groove are preferably not in contact with each other, and the clearance region between the high friction surface and the peripheral edge of the guide groove is preferably a low friction surface. .
The high friction surface is preferably outside the transfer region.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, the image forming apparatus of this embodiment is for multiple colors, and has a transfer belt means that can superimpose a toner image formed on a photoconductor on a transfer belt and transfer it onto a recording sheet. This transfer belt means is disposed in the main body of the apparatus together with the above-described photoconductor as one of the image forming apparatuses.
[0009]
FIG. 1 shows a main configuration of a transfer belt means used in this embodiment. As shown in this figure, the transfer belt means has a driving roller 1 and a holding roller 2 which are formed in a circumferential direction with a predetermined guide groove 1a supported in a rotatable manner at one end thereof, and this driving belt 1 A plurality of rollers 1 and 2 including the roller 1 are integrally and continuously wound around a transfer belt 3 including a belt base cloth 3a and a guide rib 3b. The guide rib 3b is bonded or ultrasonically welded to the inner surface of one end side in the longitudinal direction of the transfer belt 3 at a position corresponding to the guide grooves 1a and 2a of the rollers 1 and 2 for rotational driving. Sometimes, the position of the transfer belt 3 is regulated to prevent the deviation. Similarly, the holding roller 2 has a guide groove 2a corresponding to the guide rib 3b. The holding roller 2 is used for guiding and holding the transfer belt 3.
[0010]
In the operation of the transfer belt means, the transfer belt 3 is in contact with the winding surface with the drive roller 1, and when the drive roller 1 is driven to rotate by another image forming drive system, the transfer belt 3 is rotated with the winding surface. A driving force is transmitted to the transfer belt, and the transfer belt 3 is rotated. Here, in the transfer belt unit of the image forming apparatus of the present embodiment, the transfer belt 3 is driven in a partial region of the winding surface. That is, the drive roller 1 has a high friction surface 1b in a predetermined region and is in contact with all the sub-regions of the winding surface with the transfer belt 3, but of the winding surface other than the high friction surface 1b. In this region, the contact is made with low friction compared to the high friction surface 1b. Therefore, the driving roller 1 substantially drives the transfer belt 3 with the high friction surface 1b.
[0011]
FIG. 2 shows an enlarged configuration of the main part of the drive roller 1 together with a cross section of the wound transfer belt 3. As shown in this figure, the driving roller 1 is formed in a part of the vicinity of the guide groove 1a, that is, between the guide groove 1a and the transfer region 1c, and with a predetermined width over the entire circumference. It has a high friction surface 1b. As means for providing the high friction surface 1b, a rubber layer may be press-fitted or urethane coating or the like may be considered. In order to drive the transfer belt 3 with a narrow width, for example, the surface is coated with particles. It is desirable that In the present embodiment, the high friction surface 1b is coated with metal powder.
[0012]
As described above, in the image forming apparatus provided with the above-described transfer unit in which the driving roller 1 rotates and drives the transfer belt 3 only by the high friction surface 1b provided in a partial region in the vicinity of the guide groove 1a. Sometimes the transfer belt 3 does not wrinkle. That is, in the region other than the high friction surface 1b, the transfer belt 3 is a slippery low friction surface, so that it is difficult to cause wrinkles. is there.
[0013]
As shown in the figure, the high friction surface 1b is provided in a region other than the transfer region 1c, that is, a region other than the region used for transfer. By providing the high friction surface 1b at a position that does not overlap with the transfer region 1c in this way, the influence of the driving force applied to a part of the transfer belt 3 by driving on the high friction surface 1b is caused by the transfer region 1c of the transfer belt 3. It is possible to prevent the toner image from reaching the upper toner image. Further, the high friction surface 1d and the peripheral edge 1d of the guide groove 3a located in the vicinity thereof are not completely in contact with each other, and a gap region 1e is secured with a width of several millimeters. This is because if there is no gap area 1e between the peripheral edge 1d of the guide groove 1a and the high friction surface 1b, the guide rib 3b is likely to ride on the drive roller 1 and the ride will occur. This is to prevent the ride from becoming difficult to be eliminated due to friction with the scribed friction surface 1b. Here, if a low friction surface is formed in the gap region 1e, it is effective to prevent the ride-up.
[0014]
The guide groove 1a has a bottom surface that is not in contact with the guide rib 3b and is formed to have a width larger than the width of the guide rib 3b. A predetermined gap space is formed between the guide groove 3b and the guide rib. Is formed. This prevents generation of frictional resistance due to contact between the guide groove 1a and the guide rib 3b during rotational driving.
[0015]
【The invention's effect】
In the image forming apparatus according to the aspect of the invention, in the transfer belt unit, the driving roller drives the transfer belt in a part of the vicinity of the guide groove that is a part of the winding surface. do not do. Further, if the partial area of the driving roller for driving the transfer belt is a high friction surface coated with metal powder, the transfer belt is reliably driven even if the width of the high friction surface is reduced. be able to.
[0016]
Further, when the high friction surface is provided so that the high friction surface does not contact the peripheral edge of the guide groove, the guide rib can be prevented from climbing, and the high friction surface and the peripheral edge of the guide groove can be prevented. It is effective to make the gap area of the surface low in friction.
[0017]
In addition, by providing the high friction surface outside the transfer region, the influence of the driving of the high friction surface on the transfer belt does not reach the image on the transfer region, and the deterioration of the image quality can be prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a main part of a transfer belt unit according to the present invention.
FIG. 2 is a configuration diagram of a driving roller used in a transfer belt unit according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Drive roller 1a Guide groove 1b High friction surface 1c Transfer area 1d Guide groove peripheral edge 1e Guide groove peripheral edge area 3 Transfer belt 3b Guide rib

Claims (5)

A plurality of rollers including a driving roller in which guide grooves are formed in the circumferential direction outside the transfer region; a transfer belt which winds the rollers and has guide ribs at positions corresponding to the guide grooves in the longitudinal direction; The transfer belt means drives the transfer belt by the rotation of the drive roller, copies the image formed on the image carrier onto the transfer belt, and then transfers a predetermined transfer material. In the image forming apparatus for transferring to the image, the drive roller has a high friction surface on the entire circumference of a part of the area near the guide groove, and the transfer belt is driven by the high friction surface. Forming equipment. 2. The image forming apparatus according to claim 1 , wherein the high friction surface is coated with metal powder . 3. The image forming apparatus according to claim 1 , wherein the high friction surface is not in contact with a peripheral edge of the guide groove . The gap area between the high friction surface and the periphery of the guide groove is a low friction surface.
The image forming apparatus according to claim 1, characterized in that 3. The image forming apparatus according to claim 1 , wherein the high friction surface is outside a transfer region .

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